The present invention relates to hard disk drives. More specifically, the invention relates to a system and method for improving the electrical connection of a hard drive relay flexible circuit assembly to a head-gimbal assembly (HGA) flexure cable.
FIG. 1 provides an illustration of a typical hard disk drive. Hard disk drive storage devices typically include a rotating disk 1 mounted for rotation by a spindle motor 2. A slider 3, supported by an actuator arm 5, ‘flies’ over the surface of the magnetic disk 1 at a high velocity reading data from and writing data to concentric data tracks on the disk 1. The slider 3 is positioned radially by a voice coil 7 embedded in a voice coil carriage 8.
In typical hard disk drives, electrical control signals are communicated to the voice coil 7 by a relay flexible circuit 9. Typically, the relay flexible circuit 9 also communicates read/write data to the slider/head(s) 3. A printed circuit board (PCB) 11 operates to control the position of the arm(s) 5 with head/slider(s) 3 (also known as the head stack assembly (HSA)).
FIG. 2 shows a more detailed view of a head stack assembly (HSA) typical in the art. The actuator arm 5 is mounted on the actuator assembly (not shown) and affixed to a pivot member 6. The actuator arms 5 each have a suspension flexure cable (HGA flexure cable) 20 running from the heads/sliders 3 to a plurality connecting pads 19. The connecting pads 19 are electrically coupled to the flexible circuit assembly 9 by bonding (e.g., by solder bump or gold ball bonding 15) the flexure cable connecting pads 19 to a plurality of flexible circuit bonding pads 16.
FIG. 3 provides a more detailed illustration of the voice coil actuator assembly as is typical in the art. A relay flexible circuit 9 is aligned upon the coil carriage 8 by an alignment pin 17 protruding from the coil carriage 8 (inserted in a hole in a circuit board 14 terminating the flexible circuit assembly 9). After positioning, the flexible circuit assembly 9 may be electrically coupled to the HGA (not shown), as illustrated in FIGS. 2 and 4.
FIG. 4 illustrates electrically coupling the HGA flexure cable connecting pads to flexible circuit bonding pads as is typical in the art. Typically, bonding methods 15, such as solder bump or gold ball bonding, are utilized to electrically couple the HGA flexure cable connecting pads 19 to the flexible circuit bonding pads 16. As stated above, an alignment pin 17 is utilized to position the circuit board 14 of the relay flexible circuit assembly (not shown). As stated above, the circuit board 14 bonding pads 16 are electrically coupled to the flexure cable connecting pads 19 by methods such as solder bump or gold ball bonding 15.
Because this design requires the electrical bonds 15 to be placed on the inside corners formed by the extended plates 18 of the HGA flexure cable (not shown) and the circuit board 14, it is difficult to create the bonds. It is a very limited space in which to operate. The alignment of the pads 16,18 and their electrical coupling is a great challenge. The quality and efficiency of the process is adversely affected by this challenge. The tooling and equipment costs can be great because of this. In addition, a problem with soldering the electrical connection 15 between the pads 16,18 is that the bonds must be cleaned immediately after soldering. Soldering flux, which is necessary for effective soldering, must be removed. Removing the flux can be difficult and costly. Solder, which consists primarily of tin, can cause component contamination. During soldering, tin may splash out, causing damage to surrounding electrical components and/or disk media.
It is therefore desirable to have a system and method for improving the electrical connection of a hard drive relay flexible circuit assembly to a head-gimbal assembly (HGA) flexure cable that avoids the above-mentioned problems, as well as having additional benefits.